In general, the invention relates to satellite enabling navigation in terrestrial environments prone to signal reflection (multipath). More specifically, the invention relates to a method and system for optimizing a mask angle for global positioning system receivers.
The Global Positioning System (GPS) receiver concept is based on the reception of satellite signals that can be used to determine precise location, speed, and time. A number of factors heavily influence the accuracy and performance of a GPS receiver. These include for example, atmospheric effects, unwanted signal reflections (multipath), sky obstructions, and satellite geometry. To minimize the effects of the error sources, GPS receivers are often programmed with a specific xe2x80x9cmask angle.xe2x80x9d This parameter defines the minimum elevation below which satellite signals will not be used. Different receiver applications require different mask angles. For example, open-air surveying with precision GPS equipment on elevated terrain may be accurately accomplished with smaller mask angles. Aircraft, weapon, and vehicle navigation is more suited to higher mask angles in order to reduce the effects of unwanted signal reflections (multi-path) off of metallic surfaces. GPS accuracy for a spacecraft is strongly affected by the effect of multi-path on the spacecraft structure.
Typically, GPS receivers that have been designed for a particular application (for example surveying, precise time determination, or automotive navigation) are programmed with a default and fixed mask angle, unable to vary between platforms. The default mask angle for receivers is often between 5 and 15 degrees.
There are many drawbacks to low mask angle values. Low-elevation ranging measurements are more heavily affected by ionospheric and tropospheric refraction, multipath effects are much more noticeable, and horizontal obstructions can prevent reception. However, higher values reduce the receiver""s visibility to important regions of the sky. Low elevation measurements often improve accuracy by reducing dilution of precision.
Thus, there is a significant need for a method and system for optimizing the mask angle technology used in Global Positioning Systems, which overcome the above constraints, as well as other disadvantages.
One aspect of the invention provides a method for global positioning system mask angle optimization involving a reading a first entry of a mobile communication unit optimized database, the first entry indicative of a first optimal mask angle corresponding to a first placement location of a global positioning system antenna on a mobile communication unit. Next, the global positioning system antenna is operationally installed on a first placement location of the mobile communication unit in accordance with the first entry, and the first optimal mask angle is applied to a global positioning system receiver in accordance with the first entry.
Another aspect of the invention presents a system for a global positioning system mask angle optimization by providing means for reading a first entry of a mobile communication unit optimized database, the first entry indicative of a first optimal mask angle corresponding to a first placement location of a global positioning system antenna on a mobile communication unit. The system further includes means for instructing an operational installation of the global positioning system antenna on the first placement location of the mobile communication unit in accordance with the first entry, and means for instructing an application of the first optimal mask angle to a global positioning system receiver in accordance with the first entry.
Another aspect of the invention provides a computer readable medium for storing a computer program for providing a method for global positioning system mask angle optimization. The computer program is comprised of computer readable code for reading a first entry of a mobile communication unit optimized database, the first entry indicative of a first optimal mask angle corresponding to a first placement location of a global positioning system antenna on a mobile communication unit. The computer readable medium further includes computer readable code for instructing an operational installation of the global positioning system antenna on the first placement location of the mobile communication unit in accordance with the first entry, and computer readable code for instructing an application of the first optimal mask angle to a global positioning system receiver in accordance with the first entry.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiment, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.